In recent years, in head-position control of magnetic disks, feedback control has been applied to control a VCM (voice coil motor) that is to be controlled, based on filtered information of position error information of the head. Also, not only feedback control, but feed forward control may be added, based on frequency components of noise applied to a feedback control system. Furthermore, a resonance (suppression) filter may also be added in order to suppress resonant frequency components, which occur in mechanical components that constitute a part of the feedback control system. For the filtering needed in this kind of head-position control, an adaptive filter is used.
Generally, it has been common to use FFT to estimate the frequency components of the noise in the feedback control system or the resonant frequency components that occur in the mechanical components of a system. Also, while there have been many instances where the filtering of the head-position control is realized in software, it has not be easy to realize FFT in software. Also, when FFT is realized in hardware, there has been the problem of an increase in cost or an increase in the on-chip die area. That is, it has been difficult to configure the adaptive filter that could be used during feedback control of the head-position, etc.
Therefore, according to embodiments described herein, there is provided a magnetic disk device and head-position control method in which it is possible to easily configure the adaptive filter during feedback control.